[chore] Make all OTel Demo components use the http/protobuf OTLP protocol

[cyrille-leclerc]

Some OTel Demo components requires to use the grpc OTLP protocol, not supporting the default http/protobuf OTLP protocol.
This increases the complexity of the configuration.

Analysis of the current implementations. Legend:

• 🟢 : seems to support otlp http/protobuf just through env vars
• 🔴 : seems to have coded dependency on OTLP grpc
• 🟠 : unclear

service	OTLP protocol currently used	programming language	OTel SDK config file (GitHub)
accounting	unknown	C# (.NET)	unknown 🟠 (likely Program.cs or a Telemetry file)
ad	grpc (default via Java agent)	Java (agent)	Java agent via env/args (no SDK file) – Dockerfile
cart	unknown	C# (.NET)	unknown
checkout	unknown	Go	main.go 🟢
currency	unknown	C++	tracer_common.h 🔴 otlp_grpc_exporter_factory.h
email	unknown	Ruby	email_server.rb 🟢
flagd-ui	unknown	Phoenix Fwk	mix.exs 🟠 probably ok
fraud-detection	unknown	Kotlin	🟢 java agent
frontend	unknown	Node.js	Instrumentation.js 🔴 '@opentelemetry/exporter-trace-otlp-grpc'
frontend-proxy	OTLP http/protobuf (4318)	Envoy	envoy.tmpl.yaml ❓ unclear to @cyrille-leclerc
image-provider	OTLP grpc (4317)	NGINX (OTEL module)	nginx.conf.template 🔴 nginx_otel_module requires gRPC
payment	OTLP http/protobuf (Node default)	Node.js	opentelemetry.js 🔴 require('@opentelemetry/exporter-trace-otlp-grpc')
product-catalog	unknown	Go	main.go 🔴 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc
quote	unknown	PHP	routes.php... 🟠 no reference to grpc found
recommendation	unknown	Python	requirements.txt 🔴 opentelemetry-exporter-otlp-proto-grpc==1.38.0
load-generator	unknown	Python	locustfile.py 🔴 opentelemetry.exporter.otlp.proto.grpc.trace_exporter
shipping	unknown	Rust	telemetry_conf.rs 🟢 no dependency found on otlp grpc

[cyrille-leclerc]

@puckpuck I tried my best to understand the status of the services, please see above.

[cyrille-leclerc]

@tokaplan progressing on this task with:

• Update OTLP exporters to use HTTP instead of gRPC #2697